Process of preparing printing-plates



A. J. HAIN.

.PROCESS 0F PREPARING PRINTING PLATES.

APPLICATION FILEI.` JUNE Il, I9I7.`

v1,846,885. PatentedJuly 20,1920.

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Y UNITED i STATE-s -PaxrENT OFFICE.

' ALBERT J. HAIN, .oF LAKEWOOD, omo. i Y

I PRocEss or PREPARING PRINTING-maries To all whom t may concern.'

Be it known that I, ALBERT J zen of the United' States, residing atwood, in the county of Cuyahoga and State of Ohio, have invented certainnew and use- HAIN citiful Improvements in Processes of PreparinglPrinting-Plates, of which the following is a specification.

This invention relates to a process of preparing printing plates, andmore especially printing plates of the half tone variety such as are use1n newspaper, magazine and like Q less apparatus and requiringl aminimum work for printing reproductions of photos,

cuts and the like.I

The object of the invention is to provide an improved process which issimple and does away with considerable of the apparatus, such ascameras, screens and the like usually employed in process work,therebyenabling the proper effects to be obtained with amount ofskill,and adapting the process to bev performed, for example, in smalllprinting plants -or by amateurs without employment of the apparatuscustomarily found in fully equipped plants for this purpose.

Further objects of the invention are in part obvious and in in detailhereinafter..

The invention Icomprises the severalprocess steps hereinafter describedand claimed.

In the drawings Figure 'l represents a diagrammatic cross sectlonalview, enlarged,

illustrating the preparation of a pla-te' for printing by one speclficprocess embodyingthe invention; Fig. 2 is aplan view,illustrating thetreatment of and effect upon the isolated protecting areas; and E1gs. 3and 4 I are diagrammaticsectional views, enlarged,

illustrating other specific ways .of carrying out the invention.

,` of the image to: be printe and will be of greater area or highervalue where the icture is shaded or darker v than at theV hi'g erlights. This plate is usually formed by Specification of Letters Patent.

flake# part will appear more.

Patented July 20,1920.

Application feed June 11, 1917. serial N6. 174,649.

etching a smooth surfaced metal plate, such as a zinc plate, the etchingeiiect being limited to certain areas by the formation upon the plate ofa resist which prevents the etching fluid from attackin 4the plate attheareas to be unaected. he particular purpose ofthe present inventionis to provide an unproved method or process of building up upon theplate in skeleton form the' proper resist to confine the .action of theiuld to certain `desired 4.areas andI etchin prohiblt its action uponother areas.

Briefly stated, therefore, the invention coni I sists` in rst 'formingupon theplate to -be etched aseries of closely and uniformly plate from.the action of the etching fluid, and subsequently treating said spacedprowith variations in t e lights-and shadows of spaced protecting areas,all of uniform size, 'adapted inrone way or another to protect the' theimage, as a consequence of which the -I i plate finally produced, whenused as a printing plate, will reproduce the light and shadow effects ofthe image..

The invention, therefore, Aproceeds from an initi al step of firstVforming this series-of` uniformly spaced protecting'areas of uniformsize.

aid areas shouldpreferably be of what maybe termed minimum size', as

they are usually not reduced insize bya subsequent step and willtherefore` produce their counterpart'dots or stipples even in thehighest lights of the image, except as their size effect Amay bedimimshed by undercutting action ,of the etchingI fluid. The protectingother words. they `do not merge intol each other, at least so far astheir protecting effect upon the 'plate is concerned, thereby enablingthem to be built up or enlarged radially in all areas are alsoisolatedfromeachothen In directions. Nevertheless, they may be part andparcel of thejsame layer', lin or stratum, dii'erent portions `,ofwhich. are' affected in different ways to form risolated protectingareas'on the one handfand intervening areas which do .not have theotherhand.

The isolated protecting areas may be formed directly upon the surface ofthe plate tobe-etched and themselves have the quality I i vof preventlngaction on the plate by the etching fluid.v On. the other hand, itissometimes more convenient to first cover the plate `with' a -layerofaresist which will protect4 the plate 'from' acid, and upon said resist4a protecting effect', im

tectmg areas, to vary their size in accordance applying isolatedprotecting areas of a material which will serve as a resist to a reagentfor attacking the substratum or initial resist layer. In this case theisolated protecting areas are formed and built up according to thelights and shadows of the image, then used t9 protect areas of thesubstratum while attacking the intervening areas, thereby exposingl oropening up through the substratum the metal of the base 4plate to attackby the etching fluid, or even to permit attack of the base plate throughthe unaffected intervening areas Without disturbing them.

The character of resists and reagents'used is immaterial so long as theforegoing effects are obtained by the means and in the manner specified,but to more completely set forth the inventionand purely for thepurposes of illustration, I will now vdescribe several methods employingthe invention.

According to the firstmethod the plate to be etched, which may be ofzinc or'some other well known material for this purpose and which isindicated lat l, is first covered with a layer 2 of a material resistantto the particular etching fluid to be used, such as an acid-resist. Thisacid resist may be of any suitable material several of which arewellknown, for example, gum dammar, gum shellac, bitumen, dragons blood,or copper platen In the present instance, however, we will assume thatthe resist is copper plate upon the surface of the zinc.

Over the 'copper resist is applied a film 3 of a colloid or emulsion,such as gelatin or the like. After this film has been treated the plateis immersed in a suitable sensitizing solution, preferably onecontaining salts' of manganese. One solution suitable for the purpose isas follows:

c Solution Af Saturated solution potassium bichromate 5 drams. Manganoussulfate 44 grains. Manganous chlorid 22 grains. Aluminum sulfatemv. l0grains. Water to make lounces.

Aspaced isolated areas 4, shown considerably enlarged in Fig. 1, ofminimum uniform size and of hardened colloid material, in a continuouslayer wlth ntervenmg areas 5 of unaffected unhardened colloid material.At the 'Sametime exposure to light produces'a chemical effect upon thereagents in the sensitized film so that the isolated areas 4 of thehardened colloid are impregnated with an insoluble manganous oxid. Theexposed plate is then vwashed for three minutes, more 1 or less, incoldwater, or untilall the .soluble unaffected bichromate and manganoussalts are washed out. The cold water does not affect the colloid itself.f

The plate, produced as above described, is

silver, such for instance as a print which has been obtained, in thewell known manner,

with a silver bromid emulsion. Such a .print is immersed in a suitablereducing solution, for example as follows Solution B.

Copper sulfate 96 grains. Potassium bromid 48 grains. VVater 7 2 ounces.

When the image is fully bleached the print is well` washed with waterand is immersed for a minute in a solution as follows:

l The print, thus prepared, and indicated at 6, is then brought intoclose'contact with the treated colloid surface of the plate to be y usedin connection with a print 4in metallic etched, the contact beingmaintained for some time, say about twenty minutes, after which theprint is removed.

1 The effect of the contact treatment is to"l cause the manganous oXidin the isolated protecting areas of the colloid film to oxidize andrender insoluble the surrounding tis-- sues of the colloid film, as at7, in proportion to the amount of silver in the original print to bereproduced. In other words, where, in the original print a maximumamount of silver existed, as at a deep shadow, the maximum amount ofhardening action has extended into the tissues of the colloidsurrounding the several. isolated protecting areas in'that neighborhoodof the print being formed; where there was little or no silver in theoriginal print, as at a high light, there is little or no hardeningaction in the print being formed and the'isolated areas in thatneighborhood are unaffected.

The plate is next dried, alcohol being used to assist the action,.ifdesired, and is immersed in a solution of ferric chlorid 42o Baume,which quickly penetrates the colloid whereit has not been hardened orrenready for etching with a suitable acid, such as nitric acid dilutedin water.

If an acid resisting substratum, such for vfrom contact with the platethe soluble colloid may be washed out with hot water, thus exposing the-acid resisting substratum, which is removed, where unprotected, by a A,suitable solvent, such as alcohol. for shellac or turpentine forasphalt, whereupon the plate is etched with acid as before.

Up to this point I have described the formation of what may be termed abuilt up skeleton of the image upon a resisting substratum, and theremoval of the unprotected areas of the substratum to expose the baseplate for'etching. The same kind of a built up skeleton image in gelatinmay be formed directly" on the surface to be etched, which may be zinc,copper or the like, and then metal plate to convert it into a protectingenamel, so` that the burned skeleton image itself becomes a resist forthe etching fluid.

This does away with the additional resisting substratum'and the built upprotecting areas themselves become the resist, as before stated. l

In the first method described the uniform isolated protecting areas of,minimum size are built upfor increased in size in varying V- amountsaccording to the lights and shadows of the image by the effect of the'-silver inthe bromid Vprint upon the manganous oxid in the isolatedareas, and the hardening action of the twoupon the neighboring colloid Itissues, but it is not essential that the silver for producing thisaction be in a print brought into-contact or juxtaposition with thecolloid of the plate. The silver may be embodied in various ways in theplate itself,

thereby rendering the plate'suitable for direct exposure to they action'of light under anegative or in a camera. A -method of this kindfforexample, would be practised4 as fol- Upon the plate to be etched,indicated at 10, Fig. 3, is placed a suitableacid resist-4 I ingsubstratum or'layer' 11. ,Theres'ist' for this specific illustration maybe assumed to be compounded as follows Resist X Syrian asphalt-; 1ounce.

enzol l5 ounces.

Cil of lavender-; 1 dram.

Turpentine 1` dram. l

Upon the' resist are formed a seriesof closely and uniformly spacedisolated protecting areas of. uniformminifnum size,'in

dicated at 12, in which ,may be incorporated manganous oxid by the useof a solution,

.This colloid film when dried is sensitized by immersion three minutesin Soluton A, and, when dried, is exposed beneath a high-light photoengravers screen until the light has rendered insoluble those uniformlyspaced minimum sized areas exposed to the light. -The solubleA portionof the film isthen washed out in warm water, leaving upon the plate theisolated protecting areas 12,'in-V soluble and impregnated withmanganous oxid;

The plate is then flowed with an emulsion ll 'dfil 13 't' f i f saidskeleton image may be burned into the. or CO O1 m o sensl we Crm Pre er`ably containing a silver salt, such as silver bromid. One suitable.sensitized film for this purpose is compounded as follows z- Gelatingrains. Ammonium bromid 30 grains. Water 1 ounce.

Silver nitrate, 30 grains dissolved in 1 ounce of water.

vany suitabledeveloping agent yand is fixed 1n a mixture of sodiumthiosulfate (hypo7), after which the salaam D.,

lPotassium ferricyanid 5 grains, Potassium bromid 20 grains.

to render the gelatin emulsion or colloid insoluble or hard inv the.presence of silver bromid where in contact `with the oxidized isolatedprotecting areas surrounded by said .10ctplate is immersed in a solutlonas follows l ounce. f

colloid film, as at 14, the effect being'infproi portion to the exposureof each area and the deposit of silver bromid remaining in thesensitized film in the neighborhood of such area.

ter. The acid resisting substratum, where unprotected -by the remaininggelatin is dissolved in asuitable solvent, such as vturpentine', and theplate is etched with, a suitable etching medium, such as a solution ofnitric acid in Water incase the basematerial of In this lastv method'the silver deposit is After this treatment the solublel filmin theintervening spaces 15' betweenl the l isolated areas'is washed out withwarm waa created in the body offthesensitized colloid film'superposedupon previously formed isoy follows pon the plate to beietched,indicated at 20, Fig.v 4, is placed a layer 21 of a suitable resist,vsuch as Resist X' before mentioned.

, Water Upon this resist are formed the isolated protecting areas, inwhich may be incorporated a light sensitive element. lThis may beaccomplished as follows A colloid film, such as the collod or emulsion Mbefore referred to, isvfiowed over the plate andv dried, after which itlis sensitized by immersion three minutes in the following solution vSalaam E.

Potassium bichromate 10 grains.l Water 1 ounce.

The plate when' dry is exposed beneath a high light photo engraversscreen to harden the exposed areas 22, the soluble portions of the filmbeing then Washed out in water. The plate is then immersed in a Solutionas follows :5-

Solution F. l

Potassium bromid `30 grains. Acetic acid 1 drop. Water v 1ounce.

The plate is then dried and immersed in` a`r solution as follows i'Solution, G.

Silver nitrate y 30 grains. Citric acid 5 grains. 'Distilled water- 1ounce.

This treatment directly sensitizes with silver bromid the isolatedprotecting areas 22, which are formed vof `a colloid film. Theprotecting areas are then furnished with a surrounding body from whosetissues they may be Lsubsequently built up in accordance with the lightsand shadows of the image,

for which purpose the plate is flowed with a simple emulsion orcolloidfilm 23, composed, for examplefas follows Gelatin grains.

1 ounce.

y The plate, thus treated, isexposed beneath a hotogra )hic ne ative orfor some ur- P an l a a poses, in a camera, and is developed and liXedas usual. y

The plate is then treated by any suitable method to obtain the image inhalftone dot form upon the acid resisting substratum. Two such methodsmay be described for purposes of illustration. The first method is asfollows FIRST' METHOD.

T he plate isflowed with a solution as follows :e

Solution H.

Pyrogallic acid 3 grains. Citric acid 3 grains'. Water 2 ounces. A20-grain silver nitrate solution 15 drops.

This solution serves as an intensifier, increasing the deposit ofmetallic silver upon the vexposed isolated protecting areas inaccordance with the. amount of silver already present in such areas. Inother words, 1n an area containing no silver there is no further oradditional deposit, but in all areas vcontaining silver the additionalsilver deposit is in proportion to the amount already present. The plateis then immersed'in a 10%v solution of vpotassium bichromate, whichhardens the gelatin in the presence of the v metallic silVer,-and at thesame time builds up and increases the size of the isolatedprotectingareas iny accordance with the amount of' silver depositthereon, and therefore in accordance with the lights and shadows of theimage. The soluble gelatin is then washed out with warm water, the acidresisting substratum is dissolved with turpen-- tine and the plate isetched as before.

SECOND ME'rHoD. The plate, prepared with the light sensi.-

tive isolated areas thereon, may be immersedI r ina solution as' followsy f Solution I j Potassium bromid 20 grains. Potassium ferricyanid 5grains. Potassium bichromate .10 grains. y Water 1 ounce.

The purpose and effect of this solution are to tive isolated areas andthe solution, which makes insoluble the tissuesvof the plain colloidfilm neighboringsuch areasl and in direct proportion'to the amount'ofsilver 'con-L tained in such. areas'. The soluble gelatinl is thenwashed out in` warmwater, the acid resisting substratum' is dissolvedand the plate is etched, as before. Whilein the specification vI havediescribed a number of specific methods employed in the practice oftheinve'ntion, it

produce a chemical reaction between the metallic silver deposited in thelight sensif` is of course to be understood that the method is capableof considerable modification, within the scope vof the appended claims,without departing ,from thespirit of the invention, and is therefore notlimited to the specific methods described. rlllhe in.

vention can bel'carried out with simple :ippaiatus and therefore enablesplates of this kind to be prepared by amateurs or in small printingshops without a complete photol readily understood.

What I claim is l. The method of preparing plates for printingreproductions ofV an image, consisting in forming upon a plate uniformisolated protecting areas of minimum size, and increasing the sizeof-said areas in every region of the plate in accordance with thel valueof. the light or shadow inl that region of the image to be reproduced. v

2. The@ method of preparing plates for printing reproductions of animage, consisting in forming upon a plate uniform isolated protectingareas of minimumsize' surrounded by. neighboring material, andincreasing the size of said isolated areas by acy cretioii from saidmaterial in every region of the plate in accordance with the Vvalue ofthe lightA or shadow in that region of the image 'to be reproduced.

3. rlhe method-of preparing plates for printing reproductions of animage consisting in `forming upon a plate uniform-isolated protectingareas of minimum size surrounded by neighboring tissues, increasing thesize of said isolated areas by accretion from said tissues in everyregion of the plate in accordance with the value of the light or shadowin that region of the image to be reproduced, and treating the remainingintervening non-projecting areas to expose the' plate to the action ofan etching fluid.

ll. The 4method of preparing plates for printing reproductions .of animage, consisting in depositing upon a plate a uniform continuouslayer-of a material resistant to an etching fluid, super-posing uponsaid layer a series o of minimum size, increasing they size of said Aareas in every region of the plate in accordance with the value of thelight or shadow in that region vof the image`to be reproduced, anddissolving the layer of resist where exposed between the built upisolated: protecting. areas.

In testimony. whereof I afliz;v my signature.

' ALBERT J. HAIN..

uniform isolated protecting areas n

